1. Field of the Invention
The invention relates to electroslag welding with a consumable electrode and to a flux utilized in this method. The invention may be utilized in welding ingots of practically any thickness and made preferably from metals possessing high thermal conductivity, such as aluminum, copper etc.
2. Description of the Prior Art
Known in the art is a method of electroslag welding with a plate electrode (A. N. Safonnikov, "Svarka metallov plastinchatym elektrodom", K., Tekhnika, 1966, pp. 57-61).
The welding process is carried out as follows. Parts to be welded are mounted with a required gap. Then a forming device is assembled. A plate electrode mounted within an electrode holder is introduced into the gap space. A flux is charged so that the lower end of the electrode is immersed thereinto. The process of welding is initiated at a low feed speed of the plate electrode by means of short-time switchings. At the initial moment, there occurs melting of the electrical conductive flux serving as a fluxing agent for a main welding flux. As a slag pool is being formed, the flux designed for welding the parts is added in small portions. After the slag pool is formed, a stable electroslag process is established. The feed speed of the electrode is gradually increased and adjusted in accordance with a calculated speed. Prior to the termination of the welding process, due to the limited heat removal, at the edges of the parts being welded there is observed a considerable heating of edges in the upper portion of the weld butt, thereby resulting in a nonuniform penetration into the edges being welded, and in some cases even at incomplete penetrations, especially in the starting point of the weld.
The experiments have demonstrated that for the purpose of practicing the above method it is most expedient to utilize fluxes based on calcium fluoride. The main feature of these fluxes consists in that they form practically neutral slags. In the course of welding with the use of such fluxes the reliable protection of the weld pool is ensured and interaction between slag and metal is eliminated. Besides calcium fluoride, said fluxes further comprise various oxides. For instance, known in the art is a flux containing the following ingredients, percent by weight:
______________________________________ CaF.sub.2 65 to 75 CaO 18 to 30 SiO.sub.2 2 ______________________________________
However, the flux utilized in the above described method passesses inadequate activity to an oxide film, which results in the appearance of incomplete fusion in the welded joints even in the case where the penetration into the edges is sufficient.